The nation's railway trackage system has deteriorated to a point where much of the trackage is practically unusable. Much of the track in the Midwest is supported by moisture sensitive, frost susceptible subgrades, and field observations of some sections indicate that after only two years of service, approximately 3/8ths to 1/2 inch vertical rail deflections occur in normal service. If the nation's railway trackage system is to be improved, rehabilitation efforts must be undertaken before the tracks deteriorate to such a condition that they must be completely rebuilt.
The philosophy guiding current rehabilitation efforts is founded on the current state of technical knowledge as well as certain economic constraints. While several schemes for railbed improvement have been proposed, the only proven technique available is reduction of subgrade stress with ballast sections designed according to methodology dating back to approximately 1920. The recommended railbed improvement is ballast-subballast depths on the order of 18 to 24 inches, depending upon tie spacing. A fourfold increase in ballast cost in regions of aggregate scarcity is in itself a sizable obstacle to such reconstruction.
Yet another constraint on reconstruction is that hundreds or thousands of miles of railway embankments constructed 50 to 100 years ago are too narrow to accommodate thick ballast sections.
Other methods employed to stabilize the railbeds are: (1) incorporated chemicals; (2) injection; and (3) geotextiles. In the incorporated chemicals method of subgrade stabilization, the track and ties are first removed and the embankment exposed for additive incorporation through conventional highway construction techniques. In the injection method, Portland cement grout, lime, or lime-fly ash slurry is injected into the subgrade soils. The most recently developed method for stabilizing poor railroad subgrades is the use of geotextiles, usually a polyester or polypropylene fabric, placed between the ballast and subgrade. The prior art methods of subgrade stabilization are either functionally inadequate or economically unfeasible.
Therefore, it is a principal object of the invention to provide an improved support system for a railroad track.
A further object of the invention is to provide an improved method of subgrade soil stabilization.
A further object of the invention is to provide a support system for a railroad track comprising a plurality of vertically disposed arch-piles positioned below the cross ties.
A further object of the invention is to provide a support system for a railroad track wherein loads imposed on the cross ties will be distributed into the subgrade by a plurality of piles positioned below the ties and rails.
A further object of the invention is to provide a support system for a railroad track which is economical.
These and other objects will be apparent to those skilled in the art.